The use of organic trivalent phosphorus compounds, e.g. organic phosphites and phosphonites, for the stabilization of degradable polymeric substrates is well known. U.S. Pat. Nos. 4,143,028; 4,196,117; 4,318,845; 4,374,219; 4,524,166; 4,912,155; and 4,999,393 and references cited therein describe the use of seven- and eight-membered dibenzo[df][1,3,2]dioxaphosphepins and dibenzo[d,g][1,3,2]dioxaphosphocins for the stabilization of degradable polymers.
Spivack et al. in Polymer Stabilization and Degradation, P. P. Klemchuk editor; American Chemical Society: Washington D.C., 1985, 247-257 has described the use of hydrolytically stable seven- and eight-membered dibenzo[d,f][1,3,2]dioxaphosphepins and dibenzo[d,g][1,3,2]dioxaphosphocins, respectively, as processing stabilizers.
The detailed synthesis of seven- and eight-membered dibenzo[d,f][1,3,2]dioxaphosphepins and dibenzo[d,g][1,3,2]dioxaphosphocins is described by Pastor et al. in Phosphorus Sulfur, 1983, 15, 9; Phosphorus Sulfur, 1983, 15, 253; J. Heterocycl. 1983, 20, 1311; Phosphorus Sulfur, 1984, 19, 1; and Phosphorus Sulfur, 1984, 19, 285.
U.S. Pat. Nos. 4,751,319 and 4,812,501 describe stabilized compositions containing biaryl derivatives of 1,3,2-oxazaphospholidines, which are structurally distinct from the compounds of this invention. U.S. Pat. Nos. 4,599,206; 4,717,775; 4,748,261; 4,769,498 and 5,059,710 describe ligands of formula I, and III useful for transition-metal-catalyzed hydroformylation reactions. The use of compounds of formula I, and III for the stabilization of degradable organic materials is neither described nor suggested.
The instant stabilized compositions essentially comprise a degradable polymeric substrate and a compound of formula I, and III described in this invention provide superior stabilization. This is manifested in the superior processing stability of these polymeric compositions in terms of melt flow stabilization and resistance to discoloration. In addition the compositions of the instant invention exhibit superior resistance to hydrolysis prior to processing.